FAQs - Static IP addresses and IPv6

Have questions about static IP addresses and IPv6? Check out the top FAQs here.

Devices on the internet use IP addresses to locate and talk to each other, much the same way we use phone numbers or e-mail addresses to talk to or send electronic messages to specific people.

There are two kinds of IP addresses: static and dynamic. Static means the address doesn't change, and dynamic means it does change.

People lease static IP addresses when they don't want their public IP address to change. You may want to consider a static IP address if you:

  • Have a server on your network that requires external access (e-mail, FTP, web)
  • Run a service or application that requires external access (security system, video or audio services)
  • Don't want your IP address to change for any other reason (VPN, IP-PBX)

 

IPv6 is the latest version of the Internet Protocol (IP) that is the basis of how the internet is built and how it runs.

The internet was originally designed using IPv4, but after several years of enormous growth, it started to look like the world would run out of IP addresses. In 1998, IP version 6 (IPv6) was standardized. Simply put, version 6 gives the internet more IP addresses and additional features.

When you lease a static IPv4 address, it will typically have a "derived IPv6 address" associated with it, so there is no need to order anything additional. If your modem is compatible, then you just have to enable IPv6 on your modem. All of the newer modems from CenturyLink are IPv6-compatible.

Yes, the two types have different strucures.

IPv4 addresses contain only numbers in groups of two or three, separated by periods, like this: 62.157.9.98

IPv6 addresses use 4-digit groups of letters or numbers, separated by colons, like this: 2002:3e9d:9062:0001:1

If you lease a single static IP address, it only provides a public IP address to the modem. If you need a public IP address on a device behind your internet modem, you will need to lease a block of IP addresses.

When you lease a block of IP addresses, three IP addresses are reserved for routing. The other IP addresses can be assigned to devices behind your DSL modem.

CenturyLink High-Speed Internet postpaid service subscribers are eligible to lease static IP addresses. Note that static IP leases are not currently available for prepaid customers. Please visit our ordering and setup page for more information on how to order. Costs are as follows:

Block Size Monthly Rate
One Time Charge
Single IP (0 assignable*) $15 $75
8 (5 assignable) $25 $75
16 (13 assignable)
$40 $75
32 (29 assignable)
$64
$75
64 (61 assignable)
$128
$75

To enable IPv6, first confirm that your modem is IPv6-compatible. Then visit our modems and routers home page and select your modem from the drop-down lists by brand. On the support page for your modem, go to the advanced settings and click on "enable IPv6." If you have any difficulty, you can contact tech support for assistance.

CenturyLink's IPv6 address space is: 2602:0/24 

To troubleshoot IPv6:

 

CenturyLink's IPv6 address space is: 2602:0/24 

When you call CenturyLink to move your services, let us know that you have a "static IP lease", and that you want to keep them. At that time, we'll see if your current static IP(s) can be moved to your new location.

However, moving or changing your service provider may result in losing your static IP(s). Changes to your speed or your IP block size can also cause the static IP to be lost.

There are other scenarios where CenturyLink may require a change in assigned IP addresses. We will make our best effort to notify you in advance if this is necessary.

ARIN (American Registry for Internet Numbers) is a nonprofit corporation that manages the distribution of IP addresses for most of North America. (For additional information see www.arin.net)

Registering your static IPs with ARIN is a good idea because it:

  • Avoids duplicate distribution
  • Ensures traffic routing

DNS (Domain Name System) is a directory that translates names to numbers. It is like a phone book for the internet. DNS translates a domain name (e.g. www.centurylink.com) to the internet IP address at which the web site with that domain name is hosted (e.g. 155.70.40.251). Without DNS, you would need to know the IP address to get to a specific web site. However, DNS 'looks up' the address typed in to the address bar and translates it to the IP address for you, so the appropriate web page can be found and displayed.

Reverse DNS (rDNS) is the opposite directory from DNS. It translates numbers to names. rDNS translates an IP address to a domain name. The original use of the rDNS was mainly for network troubleshooting. More recently rDNS has been used as an anti-spam technique.

Some email servers may view email as spam if it originates from an IP address that does not have rDNS configured. In more extreme situations, the receiving email server will compare the originating IP address, the domain name that is listed as the sender, and then check for a rDNS record pointing back to the sender's domain name.

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